diff --git a/lib/stdalign.in.h b/lib/stdalign.in.h
index 5c2c72e2b..9d7321c31 100644
--- a/lib/stdalign.in.h
+++ b/lib/stdalign.in.h
@@ -97,7 +97,7 @@
 
    */
 
-#if !defined __STDC_VERSION__ || __STDC_VERSION__ < 201112
+#if !defined __STDC_VERSION__ || __STDC_VERSION__ < 201112 || defined __xlC__
 # if defined __cplusplus && 201103 <= __cplusplus
 #  define _Alignas(a) alignas (a)
 # elif ((defined __APPLE__ && defined __MACH__                  \